I had the same problem with my failed transmissions being so high and what solved it was remaking all the ends on my cables. do you know someone who can properly do that for you. I would also check that you are grounded properly. You need to get those failed transmissions down. here's what mine look like:
Transmit Status Transmitter ready. (TxCode
Number of Successful Transmissions 1330484
Number of Failed Transmissions 38738
Number of Packets Submitted for Transmission 238161
my transmit stats looked like yours before changing my ends, In the spring I'm going to install quad sheild cable on my system to try to make it even better.
If I were you I would first check grounding, replace cable ends if needed, or if not to much work, replace cable with quality quad shield cable. Make sure it is someone capable of doing these things properly. Five computers if used at once is quite alot for a non business Direcway plan. When checking speeds do it directly connected to the 7000 without the router, I've heard of a few routers that could slow down your connection. But I beleive your problem lies in your high failed transmission rates.